The present invention relates to a driving operation assisting technique for providing an assistance in a vehicle driving operation.
A common driving operation assisting system in the prior art uses a steering sensor for detecting the rudder angle of the steering wheel so as to estimate the vehicle tire (movement) trace according to the rudder angle of the steering wheel when moving the vehicle backward (see Japanese Laid-Open Patent Publication No. 1-14700). In this system, when moving the vehicle backward, the rear view or the rear-side view is imaged by a camera and displayed, while the vehicle tire trace which is estimated according to the rudder angle of the steering wheel being operated is superimposed on the image.
When using this system, the driving operation is as follows. That is, first, the vehicle is moved to a position where it is likely to be possible to move the vehicle into a parking space with the steering wheel being fixed. Then, in this position, the user operates the steering wheel while viewing the estimated vehicle tire trace so as to find a rudder angle at which it is likely to be possible to move the vehicle into the parking space without having to further operate the steering wheel. Then, the vehicle is moved backward while keeping the rudder angle so as to move the vehicle into the parking space. In principle, the parking operation is completed through such a driving operation.
-Problems to be Solved-
When parking a vehicle by using the system as described above, it is necessary to find a position from which the vehicle can be moved into the parking space, and then to determine the rudder angle at which to fix the steering wheel. However, it takes the user a considerable amount of practice to be skilled in such operations. Moreover, when the size, etc., of the vehicle to be driven changes, the sense of the size of the vehicle also changes, whereby the user cannot make good use of the driving know-how the user has built up while getting skilled in the operations with the previous vehicle.
Now, in the case of a parking operation, it is generally difficult to complete the driving operation while keeping the rudder angle of the steering wheel at a constant angle from the beginning of the operation, except for cases where there is no obstacle at all around the vehicle. For example, when performing parallel parking, the driver moves the vehicle from the start position to the parking position as follows. The driver first turns the steering wheel in an appropriate direction and moves the vehicle backward, and after the vehicle is moved backward to an appropriate position, the driver turns the steering wheel in the opposite direction to move the vehicle to the target position. In other words, in the case of parallel parking, it is difficult to park the vehicle while keeping the steering rudder angle at a constant angle.
Moreover, with the conventional system, if the driver moves the steering wheel even by a slight angle, a vehicle movement path is re-estimated in response to the slight change in the rudder angle, and the re-estimated path is displayed, which may confuse the driver.
Furthermore, since an actual vehicle body has some parts overhanging from the tires, the body may possibly contact an obstacle even if the tire trace does not interfere with the obstacle. Thus, in the prior art, it is difficult to precisely determine whether the vehicle parts extending beyond the tires will contact an obstacle.